Display device

ABSTRACT

An exemplary embodiment of the present disclosure provides a display device including a first substrate including a plurality of unit regions, a unit electrode portion disposed on the first substrate in one unit region, an opposed electrode facing the unit electrode portion, a liquid crystal layer interposed between the unit electrode portion and the opposed electrode, and a protrusion interposed between the first substrate and the liquid crystal layer and protruded toward the liquid crystal layer. The protrusion includes a pair of horizontal portions facing each other and including a side parallel to a first direction, a pair of vertical portions facing each other and including a side parallel to a second direction different from the first direction, and at least one corner portion including a first oblique side parallel to a direction oblique with respect to the first and second directions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 15/220,288 filed on Jul. 26, 2016, which claims priority to thebenefit of Korean Patent Application No. 10-2015-0119127 filed in theKorean Intellectual Property Office on Aug. 24, 2015, the entirecontents of which are incorporated herein by reference.

BACKGROUND (a) Technical Field

The present disclosure is related to a display device, and moreparticularly, to a liquid crystal display of a vertical alignment (VA)mode.

(b) Description of the Related Art

A display device, such as a liquid crystal display (LCD), an organiclight emitting diode (OLED) display, or the like, generally includes adisplay panel including a plurality of pixels for displaying an image.

The display panel of a liquid crystal display includes a liquid crystallayer including liquid crystal molecules, an electric field generatingelectrode for controlling alignment of the liquid crystal molecules inthe liquid crystal layer, a plurality of signal lines for applying avoltage to at least some of the electric field generating electrodes,and a plurality of switching elements connected thereto. When a voltageis applied to the electric field generating electrode, an electric fieldis generated in the liquid crystal layer, thereby realigning the liquidcrystal molecules. Accordingly, an image may be displayed by adjustingan amount of transmitted light. The display panel may include at leastone polarizer to control an amount of transmitted light.

The electric field generating electrode included in the liquid crystaldisplay includes a pixel electrode for receiving a data voltage and anopposed electrode for receiving a common voltage. The pixel electrodemay receive a data voltage through the switching element, which may beformed of, e.g., a thin film transistor. The pixel electrode and theopposed electrode may be configured to face each other with the liquidcrystal layer interposed therebetween, or may be disposed on the sameside with respect to the liquid crystal layer.

Each pixel may display a primary color, such as red, green, blue, or thelike.

Among liquid crystal displays, there is a vertical alignment (VA) modein which liquid crystal molecules are arranged such that major axesthereof are aligned mainly vertically with respect to a surface of thedisplay panel when an electric field is not applied to the liquidcrystal layer. A liquid crystal display implementing the verticalalignment (VA) mode generally has a high contrast ratio and a widestandard view angle in comparison with other liquid crystal displays.

To achieve a wide view angle in a liquid crystal display implementingthe vertically aligned mode, a plurality of subregions or domains havingdifferent alignment directions of liquid crystal molecules may be formedin one pixel. An example of a method for forming a plurality of domainsmay include forming a cutout, such as a slit, in the electric fieldgenerating electrode. In the case in which a cutout is formed in theelectric field generating electrode, a fringe field is formed by an edgeof the cutout, which realigns the liquid crystal molecules. Accordingly,a plurality of domains may be formed.

The liquid crystal molecules in each domain or subregion are tiltedmainly in the same direction.

An initial alignment method is used for hastening a response speed andimplementing a wide viewing angle. The initial alignment method providesa pretilt to the liquid crystal when an electric field is not applied toa liquid crystal layer. In order to provide pretilts having variouspredetermined directions to the liquid crystal molecules, an alignmentlayer having various alignment directions may be employed, or analignment aid may be added to a liquid crystal layer or an alignmentlayer and cured after applying an electric field to the liquid crystallayer.

However, to manufacture a liquid crystal display including an alignmentaid for a pretilt, an additional process line for an alignment aid, anultraviolet ray curing process, and the like are often required, whichwould lead to extra cost. Therefore, problems of increasingmanufacturing cost of a liquid crystal display, requiring additionalmanufacturing equipment, and complicating a manufacturing process exist.The above information disclosed in this Background section is only forenhancement of understanding of the background of the present disclosureand therefore may contain information that does not form the prior artthat is already known in this country to a person of ordinary skill inthe art.

SUMMARY

The present disclosure describes a liquid crystal display havingadvantages of being capable of increasing liquid crystal alignmentcontrollability and transmittance thereof.

An exemplary embodiment of the present disclosure provides a displaydevice including: a first substrate including a plurality of unitregions; a unit electrode portion disposed on the first substrate anddisposed in one unit region; an opposed electrode facing the unitelectrode portion; a liquid crystal layer including a plurality ofliquid crystal molecules interposed between the unit electrode portionand the opposed electrode; and a protrusion interposed between the firstsubstrate and the liquid crystal layer and protruded toward the liquidcrystal layer, wherein the protrusion includes: a pair of horizontalportions facing each other with respect to a center of the unitelectrode portion and including a side parallel to a first direction; apair of vertical portions facing each other with respect to the centerof the unit electrode portion and including a side parallel to a seconddirection different from the first direction; and at least one cornerportion including a first oblique side parallel to a direction obliquewith respect to the first and second directions.

The first oblique side and the first direction may form an acute anglethat is equal to or greater than about 40° and less than about 90°.

The horizontal portion and the vertical portion may extend around atleast a part of a light transmitting region included in the unit region.

The protrusion may include a first lateral surface obliquely tilted withrespect to a bottom surface of the protrusion.

The unit region may include a plurality of subregions at which theliquid crystal molecules are tilted in different directions from eachother when an electric field is generated in the liquid crystal layer,and the liquid crystal molecules disposed on the first lateral surfacemay have a pretilt in a direction to which the liquid crystal moleculesare to be tilted in each of the subregions.

The first lateral surface and the bottom surface of the protrusion mayform an angle in a range of about 40° to about 50°.

The protrusion may be included in a light blocking region having lowerlight transmittance than the light transmitting region.

The unit electrode portion may include a stem disposed at a boundarybetween adjacent ones of the subregions and a plurality of branchesconnected to the stem, and the branches may be extended toward adifferent direction from the first and second directions.

The unit electrode portion may include at least one planar portiondisposed in at least one corner of the unit electrode portion.

The planar portion may include a second oblique side extended toward anoblique direction with respect to the first direction, and the secondoblique side may be disposed internally in the subregions.

The first oblique side may overlap the planar portion.

The second oblique side may be spaced apart from the branches facing thesecond oblique side.

Sides of end portions of the branches may overlap the protrusion.

The first lateral surface and the bottom surface of the protrusion mayform an angle in a range of about 1° to about 2°.

An occupied area of the corner portion within one correspondingsubregion is equal to or less than about 50%.

The corner portion may be included in the light transmitting region.

A maximum thickness of the corner portion is equal to or less than about0.5 μm.

The display device may further include a second substrate facing thefirst substrate with the liquid crystal layer interposed between thefirst substrate and the second substrate, and a spacer disposed on thefirst substrate, while the protrusion and the spacer may be disposed ina same layer and may include a same material.

Further, the display device may include a main light blocker disposed inthe same layer as the spacer and the protrusion, including the samematerial as the spacer and the protrusion, having a thickness of lessthan a thickness of the spacer, and the main light blocker may bedisposed in a light blocking region.

The first oblique side may be connected to a side of the horizontalportion or the vertical portion.

The display device may include a pixel configured to display an image incorrespondence to one image signal, and the pixel may include aplurality of unit regions.

Another embodiment of the present disclosure provides a display deviceincluding: a first substrate including a plurality of unit regions; aunit electrode portion disposed on the first substrate and disposed inone unit region of the plurality of unit regions; an opposed electrodefacing the unit electrode portion; and a liquid crystal layer includinga plurality of liquid crystal molecules interposed between the unitelectrode portion and the opposed electrode, wherein the unit regionincludes a plurality of subregions at which the liquid crystal moleculesare tilted in different directions from each other when an electricfield is generated in the liquid crystal layer, and the unit electrodeportion includes a stem disposed at a boundary between adjacentsubregions, a plurality of branches connected to the stem, and at leastone planar portion disposed in at least one corner of the unit electrodeportion.

The planar portion may include an oblique side extended toward anoblique direction with respect to an extended direction of the stem, andthe oblique side may be disposed internally in the subregions.

The oblique side may be spaced apart from the branches facing theoblique side.

A ratio of an occupied area of the planar portion in a correspondingsubregion may be equal to or less than about 50%.

According to an exemplary embodiment of the present disclosure, adisplay device may improve liquid crystal alignment controllability andtransmittance thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a layout view of a display device according to an exemplaryembodiment of the present disclosure.

FIG. 2 and FIG. 3 are top plan views illustrating a plurality of unitregions in a pixel of a display device according to an exemplaryembodiment of the present disclosure.

FIG. 4 is a top plan view illustrating a protrusion and an alignmentdirection of liquid crystal molecules in a unit region of a displaydevice according to an exemplary embodiment of the present disclosure.

FIG. 5 is an exemplary cross-sectional view of FIG. 4 taken along theline V-V′.

FIGS. 6, 7, 8, 9, 10, 11, 12 and 13 are top plan views illustrating astructure of a protrusion and a unit electrode portion in a unit regionof a display device according to an exemplary embodiment of the presentdisclosure.

FIG. 14 is an exemplary cross-sectional view of FIG. 13 taken along theline XIV-XIV′.

FIG. 15 is a top plan view illustrating a structure of a protrusion anda unit electrode portion in a unit region of a display device accordingto an exemplary embodiment of the present disclosure.

FIG. 16 is a layout view illustrating a pixel of a display deviceaccording to an exemplary embodiment of the present disclosure.

FIG. 17 is a layout view additionally illustrating a protrusion in thepixel of FIG. 16.

FIGS. 18, 19 and 20 are exemplary cross-sectional views of FIG. 17 takenalong the line XVII-XVII′.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present system and method are described more fully hereinafter withreference to the accompanying drawings in which exemplary embodiments ofthe present system and method are shown. As those skilled in the artwould realize, the described embodiments may be modified in variousdifferent ways, all without departing from the spirit or scope of thepresent disclosure.

In the drawings, the thicknesses of layers, films, panels, regions,etc., are exaggerated for clarity. Like reference numerals designatelike elements throughout the specification. When an element such as alayer, film, region, or substrate is referred to as being “on” anotherelement, it may be directly on the other element, or interveningelements may also be present. In contrast, when an element is referredto as being “directly on” another element, there are no interveningelements present.

To avoid diluting the relevant subject matter, parts that are generallyknown to those of ordinary skill in the art may be omitted from thedescription herein, and like numerals refer to like or similarconstituent elements throughout the specification.

Throughout this specification and the claims that follow, when it isdescribed that an element is “coupled” to another element, the elementmay be “directly coupled” to the other element or “electrically coupled”to the other element through a third element. In addition, unlessexplicitly described to the contrary, the word “comprise” and variationssuch as “comprises” or “comprising” imply the inclusion of statedelements but not the exclusion of any other elements.

First, a display device according to an exemplary embodiment of thepresent disclosure is described with reference to FIG. 1 to FIG. 3.

Referring to FIG. 1, the display device according to the exemplaryembodiment of the present disclosure includes a display panel 300. Thedisplay panel 300 includes a display area DA in which a plurality ofpixels PX are arranged, and a plurality of signal lines are disposed inthe display area DA. A plurality of pixels PX may be arrangedsubstantially in a matrix form, but they are not limited thereto.

The pixels PX are disposed in the display area of the display panel 300to display an image according to an image signal, and may display aprimary color, such as red, green, blue, or the like. Various colors maybe displayed by adjusting the luminance of a plurality of pixels PXhaving different colors.

One pixel PX may include at least one light transmitting area havingrelatively high light transmittance and at least one light blocking areahaving no or relatively low light transmittance.

The signal line includes a plurality of gate lines GL1-GLn fortransferring a gate signal to control turn on and off of a switchingelement and a plurality of data lines DL1-DLm for transferring a datavoltage. The gate lines GL1-GLn are extended to a first direction D1,and the data lines DL1-DLm are extended to a second direction D2 that isdifferent from the first direction D1. The second direction D2 may beperpendicular to the first direction D1, and the first direction D1 andthe second direction D2 are on the same plane when the display panel 300is viewed from a vertical direction with respect to a plane of thedisplay panel 300.

The display panel 300 may include at least one switching elementdisposed in an area corresponding to one pixel PX and at least one pixelelectrode connected thereto. The switching element may include at leastone thin film transistor connected to at least one data line DLj (j=1,2, . . . , or m) and at least one gate line GLi (i=1, 2, . . . , or n).The thin film transistor may transfer a data voltage to the pixelelectrode through the data line DLj controlled according to a gatesignal transferred through the gate line GLi.

In view of a cross-sectional structure, the display panel 300 of theliquid crystal display includes at least one liquid crystal layer, andthe liquid crystal layer includes a plurality of liquid crystalmolecules. The liquid crystal molecules may be initially aligned in asubstantially vertical direction with respect to the plane of thedisplay panel 300. To that end, the display panel 300 may include atleast one vertical alignment layer adjacent to the liquid crystal layer.Herein, the plane of the display panel 300 designates a plane extendedin a direction parallel to the first and second directions D1 and D2.

Referring to FIG. 2 and FIG. 3, one pixel PX includes at least one unitregion SP. Particularly, in the case in which one pixel PX includes aplurality of unit regions SP, the unit region SP may have a uniform ornon-uniform area.

In the case in which one pixel PX includes a plurality of unit regionsSP, the unit regions SP included in one pixel PX may be arranged in aquadrangular matrix form as illustrated in FIG. 2. FIG. 2 illustrates anexample in which one pixel PX includes six unit regions SP arranged in a3×2 matrix form, but this exemplary embodiment of the present disclosureis not limited thereto.

A plurality of unit regions SP included in one pixel PX may beconfigured in two separated regions interposing a thin film transistorregion TRA including a thin film transistor therebetween as illustratedin FIG. 3. For example, a plurality of unit regions SP arranged in a 2×2matrix form may be disposed in an upper part with respect to the thinfilm transistor region TRA and a plurality of unit regions SP arrangedin a 3×2 matrix form may be disposed in a lower part with respect to thethin film transistor region TRA, but the present exemplary embodiment isnot limited thereto.

The thin film transistor region TRA may correspond to a light blockingregion through which little or no light is transmitted. Most portions ofthe unit region SP may serve as a light transmitting region.

One pixel PX of the display device according to the exemplary embodimentof the present disclosure may include a plurality of subpixels PXa andPXb for displaying an image of a luminance depending on identical ordifferent gamma curves corresponding to an image signal. Referring toFIG. 3, the first subpixel PXa included in one pixel PX may include aplurality of unit regions SP at one side with respect to the thin filmtransistor region TRA, and the second subpixel PXb included in one pixelPX may include a plurality of unit regions SP at an opposite side withrespect to the thin film transistor region TRA. In a medium gray, anumber of the unit regions SP included in the second subpixel PXb may bemore than a number of the unit regions SP included in the first subpixelPXa when the second subpixel PXb displays an image having lowerluminance than that of the first subpixel PXa.

Next, a specific structure of the unit region SP of a display deviceaccording to an exemplary embodiment of the present disclosure isdescribed with reference to FIG. 4 and FIG. 5 along with above-describedFIG. 1 to FIG. 3.

Referring to FIG. 4, one unit region SP includes a plurality ofsubregions A1, A2, A3, and A4, when viewed in a planar structure. Liquidcrystal molecules 31 included in each of subregions A1, A2, A3, and A4are realigned such that the directions of their major axes arerespectively different from each other when an electric field isgenerated in the liquid crystal layer. The major axes of the liquidcrystal molecules 31 are initially aligned to be perpendicular withrespect to a plane of the display panel 300, and are tilted andrealigned in a direction parallel to a plane of the display panel 300according to the generated electric field.

For example, as illustrated in FIG. 4, in the case in which one unitregion SP includes four subregions A1, A2, A3, and A4, the liquidcrystal molecules 31 disposed in each of subregions A1, A2, A3, and A4are tilted in respectively different directions a1, a2, a3, and a4. Thedirections a1, a2, a3, and a4 in which the liquid crystal molecules 31are mainly tilted are different from the first and second directions D1and D2. For example, the tilting directions a1, a2, a3, and a4 of theliquid crystal molecules 31 in each of subregions A1, A2, A3, and A4 maybe in a range of about 40° to about 50° or about 130° to about 140° withrespect to the first direction D1 or the second direction D2, but theyare not limited thereto. The tilting direction a1 of the liquid crystalmolecules 31 in the first subregion A1 is opposite to the tiltingdirection a3 of the liquid crystal molecules 31 in the third subregionA3, and the tilting direction a2 of the liquid crystal molecules 31 inthe second subregion A2 is opposite to the tilting direction a4 of theliquid crystal molecules 31 in the fourth subregion A4. Vectorcomponents in the first direction D1 of the tilting directions a1, a2,a3, and a4 of the liquid crystal molecules 31 in a pair of subregions ofA1, A2, A3, and A4 that are adjacent to each other along the firstdirection D1 or the second direction D2 may be opposite to each other.Further, the tilting directions a1, a2, a3, and a4 of the pair ofadjacent subregions of A1, A2, A3, and A4 along the first direction D1or the second direction D2 may form an angle in a range of 85° to 95°,but they are not limited thereto.

Most regions of the subregions A1, A2, A3, and A4 serve as lighttransmitting regions.

Referring to FIG. 4 and FIG. 5, one unit region SP includes a protrusion261 for controlling an alignment direction of the liquid crystalmolecules 31. The pixel PX (not shown) may include the pixel electrodethat is one of electrodes for generating an electric field in the liquidcrystal layer, and the protrusion 261 may be interposed between thepixel electrode and the liquid crystal layer. The protrusion 261, asillustrated in FIG. 5, may provide a pretilt to the liquid crystalmolecules 31 by protruding toward the liquid crystal layer, therebycontrolling the tilting direction of the liquid crystal molecules 31. Across-sectional position of the protrusion 261 may be disposed onanother layer having a surface that is formed to protrude toward theliquid crystal layer.

Referring to FIG. 4, when viewed from a planar structure, the protrusion261 includes a pair of horizontal portions 261 a configured to face eachother with respect to a center C of the unit region SP and eachincluding a side parallel to the first direction D1, a pair of verticalportions 261 b configured to face each other with respect to the centerC of the unit region SP and each including a side parallel to the seconddirection D2, and a corner portion 261 c including an oblique side Eaparallel to a direction oblique to the first and second directions D1and D2.

The horizontal portion 261 a and the vertical portion 261 b that areadjacent to each other may be connected to each other as illustrated inFIG. 4, or may be spaced apart from each other. A width of thehorizontal portion 261 a and a width of the vertical portion 261 b maybe the same or may be different from each other.

The corner portion 261 c is interposed between the horizontal portion261 a and the vertical portion 261 b that are adjacent to each other.The corner portion 261 c may be in a shape of substantially a triangleincluding the oblique side Ea. The other two sides of the corner portion261 c except for the oblique side Ea may be substantially parallel tothe first and second directions D1 and D2, respectively. The obliqueside Ea of the corner portion 261 c, as illustrated in FIG. 4, may beconnected to adjacent sides of the horizontal portion 261 a and thevertical portion 261 b, or spaced apart therefrom with a predetermineddistance therebetween.

The pair of horizontal portions 261 a, the pair of vertical portions 261b, and the four corner portions 261 c may be connected to each other tosubstantially constitute a closed curve. In this case, the protrusion261 may have a substantially quadrangular shape.

The oblique side Ea of the corner portion 261 c may form an angle Angwith the first direction D1 to be greater than about 40° and less thanabout 90°. Herein, the angle Ang is an acute angle. An extendingdirection of the oblique side Ea may cross the tilting directions a1,a2, a3, and a4 of the liquid crystal molecules 31 in subregions A1, A2,A3, and A4, respectively. More specifically, an angle of the crossingmay be substantially 90°.

A distance W2 between the oblique side Ea of the corner portion 261 cand a vertex formed to face the oblique side Ea may be equal to or lessthan a width W1 of the horizontal portion 261 a or the vertical portion261 b, but is not limited thereto.

The protrusion 261 is formed around at least a part of the lighttransmitting region of the unit region SP. FIG. 4 illustrates an examplein which the protrusion 261 forms a closed curve surrounding a pluralityof subregions A1, A2, A3, and A4 included in the unit region SP. Theprotrusion 261 may correspond to a light blocking region surrounding thelight transmitting region, but is not limited thereto.

Referring to FIG. 4 and FIG. 5, the protrusion 261 includes a lateralsurface Sa that serves as a slope obliquely tilted with respect to abottom surface of the protrusion 261 when viewed from a cross-sectionalstructure. A cross-sectional angle Ang1 between the lateral surface Saand the bottom surface of the protrusion 261 may be in a range of about40° to about 50°, but is not limited thereto, and may vary depending ona material characteristic or a manufacturing process of the protrusion261.

The protrusion 261 may include a pair of lateral surfaces Sa configuredto face each other, and a top side therebetween may be substantiallyparallel to the bottom surface of the protrusion 261. However, in somecases, the top side of the protrusion 261 substantially parallel to thebottom surface thereof may be omitted.

A maximum height H1 of the protrusion 261 from the bottom surfacethereof, i.e., the maximum thickness may be in a range of about 0.5 μmto about 1.2 μm, but is not limited thereto, and may vary depending on adesign condition.

The oblique side Ea of the corner portion 261 c corresponds to a bottomside of the lateral surface Sa of the corner portion 261 c.

A vertical alignment layer may be disposed on a surface of theprotrusion 261. Accordingly, the liquid crystal molecules 31 around thesurface of the protrusion 261 may be aligned in a substantiallyperpendicular direction to the surface of the protrusion 261.

When the alignment of the liquid crystal molecules 31 substantiallyperpendicular to a plane of the display panel 300 is determined as areference alignment, the protrusion 261 controls the liquid crystalmolecules 31, particularly those adjacent to the lateral surface Sa, tohave a pretilt toward each interior portion of the subregions A1, A2,A3, and A4 even when an electric field is not generated in the liquidcrystal layer. A pretilt direction forms an acute angle together with adirection of the reference alignment substantially vertical to the planeof the display panel 300, and the acute angle therebetween may begreater than about 30°.

Particularly, the corner portion 261 c of the protrusion 261 controlsthe liquid crystal molecules 31 adjacent thereto to have the pretilttoward the tilting directions a1, a2, a3, and a4.

Such pretilt of the liquid crystal molecules 31 by the protrusion 261may provide faster alignment of the liquid crystal molecules 31 disposedin each of the subregions A1, A2, A3, and A4 in respective tiltingdirections a1, a2, a3, and a4 when an electric field is generated in theliquid crystal layer.

Particularly, since the direction perpendicular to the oblique side Eaof the corner portion 261 c substantially faces the center C of the unitregion SP, the liquid crystal molecules 31 positioned around the cornerportion 261 c already have a pretilt in the tilting directions a1, a2,a3, and a4 in which the liquid crystal molecules 31 are tilted when anelectric field is generated in the liquid crystal layer. Accordingly,the liquid crystal molecules 31 may be realigned faster in the tiltingdirections a1, a2, a3, and a4, thereby improving the response speed andtransmittance thereof.

In the case in which the angle Ang is about 45°, the corner portion 261c may control the liquid crystal molecules 31 disposed in the subregionsA1, A2, A3, and A4 to be aligned faster in a direction toward the centerC thereof. In the case in which the angle Ang is greater than about 45°,the corner portion 261 c may control the liquid crystal molecules 31 tohave an angle that is less than about 45° between the tilting directionsa1, a2, a3, and a4 thereof and the first direction D1. In this case, theliquid crystal molecules 31 may be tilted in a direction closer to thefirst direction D1 than the second direction D2 when an electric fieldis generated in the liquid crystal layer. Accordingly, side visibilitymay be improved.

If the liquid crystal layer of the display panel 300 is pressed by anexternal pressure, and thus an alignment of the liquid crystal molecules31 is in disorder, even though the external pressure is removed, thealignment of the liquid crystal molecules 31 may not be recovered,thereby being seen as spots. However, according to the exemplaryembodiment of the present disclosure, the protrusion 261 may control thealignment of the liquid crystal molecules 31 that are adjacent theretoin a predetermined direction. This facilitates the recovery of theliquid crystal molecules 31 in each of the subregions A1, A2, A3, and A4to the original alignment direction. That is, after an external pressureis removed, the recovery speed at which the alignment of the liquidcrystal molecules 31 returns from disorder is improved. Particularly,the corner portion 261 c of the protrusion 261 may support fasterrecovery to the tilting directions a1, a2, a3, and a4.

As such, according to the exemplary embodiment of the presentdisclosure, when an image is displayed by generating an electric fieldin the liquid crystal layer, the liquid crystal molecules 31 may berealigned faster in a target alignment direction due to the protrusion261, so the transmittance may be further improved, and an image closerto a target luminance may be displayed, thereby improving the displayquality.

According to an exemplary embodiment of the present disclosure, theprotrusion 261 may include an organic material. In a manufacturingprocess of the display device according to an exemplary embodiment ofthe present disclosure, the protrusion 261 may be formed by coating anorganic material and then using a photolithographic process withexposure using a photomask and development. In this case, lighttransmittance of the photomask corresponding to the protrusion 261 mayhave a constant value.

A detailed structure of a unit region SP of a display device accordingto an exemplary embodiment of the present disclosure is described withreference to FIG. 6 to FIG. 12, as well as above-described FIG. 1 toFIG. 5. The same constituent elements as in the above-describedexemplary embodiments are designated by the same reference numerals, anddescriptions thereof are omitted. While focusing on different elements,detailed descriptions are provided.

First, referring to FIG. 6, a display device according to the presentexemplary embodiment is substantially the same as aforementionedexemplary embodiments, while a structure of the pixel electrode is morespecified in this exemplary embodiment.

Referring to FIG. 6, a unit electrode portion 191 is disposed in oneunit region SP. In the case in which one pixel PX includes a pluralityof unit regions SP, the unit electrode portion 191 may be a part of apixel electrode disposed in the pixel PX, and in the case in which onepixel PX includes one unit region SP, the unit electrode portion 191 maybe a pixel electrode itself.

An overall shape of the unit electrode portion 191 is substantially aquadrangle, and includes a cross-shaped stem 195 including a horizontalstem and a vertical stem intersecting the horizontal stem, and aplurality of branches 197. A center of the cross-shaped stem 195 maysubstantially coincide with the center C of the unit region SP.

The cross-shaped stem 195 is extended along a boundary between thesubregions A1, A2, A3, and A4 of the unit region SP. In other words, theunit region SP is divided into the subregions A1, A2, A3, and A4 by thecross-shaped stem 195. The horizontal stem of the cross-shaped stem 195may extend in a direction parallel to the first direction D1, and thevertical stem thereof may extend in a direction parallel to the seconddirection D2.

A width of the cross-shaped stem 195 may be in a range of about 4 μm toabout 6 μm, but is not limited thereto.

The branches 197 are connected to the cross-shaped stem 195 and extendoutward from the cross-shaped stem 195. The branches 197 are disposed inthe subregions A1, A2, A3, and A4, and a slit excluding an electrode isdisposed between adjacent branches 197 disposed in each of thesubregions A1, A2, A3, and A4. Intersecting positions of the branches197 of a pair of subregions of A1, A2, A3, and A4 adjacent to each otheralong the first direction D1 or the second direction D2 with thecross-shaped stem 195 may not be disposed coincidently, but may bedisposed alternately.

Pitches of the branches 197 and the slit may be in a range of about 5 μmto about 8 μm, but are not limited thereto. Further, a ratio of widthsof the branches 197 and the slit may be in a range of about 1.5:1 toabout 1:1.5, but is not limited thereto, and may be appropriatelyadjusted in consideration of a display characteristic.

Among the four subregions A1, A2, A3, and A4 of the unit region SP, thebranches 197 disposed in the first subregion A1 obliquely extend towardthe upper right direction from the cross-shaped stem 195, the branches197 disposed in the second subregion A2 obliquely extend toward theupper left direction from the cross-shaped stem 195, the branches 197disposed in the third subregion A3 obliquely extend toward the lowerleft direction from the cross-shaped stem 195, and the branches 197disposed in the fourth subregion A4 obliquely extend toward the lowerright direction from the cross-shaped stem 195.

Although not illustrated, at least some of end portions of the branches197 may be connected to each other to form an outer circumference of theunit electrode portion 191.

An acute angle between the branches 197 and an extending direction ofthe horizontal stem of the cross-shaped stem 195 may be in a range of40° to about 50°, but is not limited thereto, and may be appropriatelyadjusted in consideration of a display characteristic such as visibilityof the display device.

According to the exemplary embodiment of the present disclosure, theunit region SP may include the above-described protrusion 261, and theprotrusion 261 may be disposed above or below the unit electrode portion191. Hereinafter, an example in which the protrusion 261 is disposed onthe unit electrode portion 191 is mainly described.

The sides of end portions of the branches 197 may or may not overlap theprotrusion 261. FIG. 6 illustrates an example in which a side of an endportion of the branches 197 overlaps the protrusion 261. In this case,efficiency of a light transmitting region of the unit region SP may beimproved.

The display panel 300 may further include an opposed electrode (notillustrated in FIG. 6) configured to face the unit electrode portion 191interposing the liquid crystal layer therebetween. The opposed electrodeserves as a field generating electrode generating an electric field inthe liquid crystal layer together with the pixel electrode. A voltagedifference between a data voltage applied to the pixel electrode and avoltage applied to the opposed electrode may vary depending on a gray ofan image signal corresponding to the pixel PX. Opposed electrodesdisposed in a plurality of pixels PX of the display panel 300 may beconnected to each other to transfer the same voltage. The opposedelectrodes may be formed in a shape of a unitary plate without anycutout.

Hereinafter, a display operation of the display device according to anexemplary embodiment of the present disclosure is described.

When a thin film transistor connected to the pixel electrode includingthe unit electrode portion 191 is turned on, a data voltage is appliedto the pixel electrode. Then, the opposed electrode to which a constantvoltage, such as a common voltage, is applied generates an electricfield in the liquid crystal layer together with the pixel electrode. Theelectric field includes a perpendicular component substantiallyperpendicular to a plane of the display panel 300, and the liquidcrystal molecules 31 tend to be tilted in a substantially paralleldirection to the plane of the display panel 300 by the perpendicularcomponent of the electric field. In this case, edges of the branches 197of the unit electrode portion 191 may generate a fringe field. Theliquid crystal molecules 31 around the branches 197 are tilted by thisfringe field toward insides of the branches 197. As a result, the liquidcrystal molecules 31 are tilted mostly to the center C and are tilted toa direction substantially parallel to an extending direction of thebranches 197. Accordingly, tilting directions of the liquid crystalmolecules 31 in four subregions A1, A2, A3, and A4 are different fromeach other, and may be the same as the above-described tiltingdirections a1, a2, a3, and a4 of the liquid crystal molecules 31illustrated in FIG. 4.

As described above, the protrusion 261 may improve controllability forrealigning the liquid crystal molecules 31 (referred to as liquidcrystal alignment controllability) and response speed by providing thepretilt to the liquid crystal molecules 31. Particularly, the cornerportion 261 c of the protrusion 261 may further improve the liquidcrystal alignment controllability and the response speed of the liquidcrystal molecules 31 by providing the pretilt close to the tiltingdirections a1, a2, a3, and a4 of the liquid crystal molecules 31 as in aregion Ra illustrated in FIG. 6. Other effects of the protrusion 261 arethe same as those of the aforementioned descriptions.

According to the exemplary embodiment of the present disclosure,sufficient controllability of the liquid crystal molecules 31 may besecured without including an alignment aid to an alignment layer or aliquid crystal layer, unlike a conventional art. Accordingly, a displaydevice having improvements in liquid crystal alignment controllabilityand transmittance may be provided without adding a complex manufacturingprocess for forming an alignment aid.

Further, liquid crystal alignment controllability of the liquid crystalmolecules 31 may be improved without deterioration of transmittance whenone pixel PX includes a plurality of unit regions SP and a size of thepixel PX is increased.

Next, referring to FIG. 7, a display device according to the presentexemplary embodiment is the same as most of the aforementioned exemplaryembodiment illustrated in FIG. 6, while sides of end portions of thebranches 197 of the unit electrode portion 191 may not be overlappedwith the protrusion 261. A distance d1 between the sides of end portionsof the branches 197 and a side of an inner edge of the protrusion 261may be equal to or greater than 0 μm and may be equal to or less thanabout 1 μm.

According to the present exemplary embodiment, the display device mayhave improved side visibility.

Next, referring to FIG. 8, a display device according to the presentexemplary embodiment is the same as most of the aforementioned exemplaryembodiment illustrated in FIG. 6, while the oblique side Ea of thecorner portion 261 c of the protrusion 261 and the first direction D1may form the angle Ang to be greater than about 45°. In this case, thetilting directions a1, a2, a3, and a4 of the liquid crystal molecules 31by the corner portion 261 c and the first direction D1 may be controlledto form an angle therebetween of less than about 45°. As a result, whenan electric field is generated in the liquid crystal layer, the liquidcrystal molecules 31 may be tilted in a direction closer to the firstdirection D1 than the second direction D2, so the side visibility may beimproved.

Next, referring to FIG. 9, a display device according to the presentexemplary embodiment is the same as most of the aforementioned exemplaryembodiment, while the unit electrode portion 191 may have a differentstructure.

The unit electrode portion 191 is the same as most of the unit electrodeportion 191 of the aforementioned exemplary embodiment, while at leastone planar portion 198 in a shape of a unitary plate may be disposed inat least one of four corners thereof. In the case in which the unitelectrode portion 191 is of a substantially quadrangle shape, at leastone planar portion 198 is disposed in at least one corner of thequadrangle. FIG. 9 illustrates an example in which each planar portion198 is disposed in four corners of the unit electrode portion 191.

An electrode forming the planar portion 198 has no pattern thereon, sohas a continuous surface without an opening such as a slit.

One planar portion 198 may be a polygon, for example, a triangle,including an oblique side Eb disposed at an interior of one of thesubregions A1, A2, A3, and A4. The planar portion 198 may be of atriangle shape including a first vertex corresponding to a vertex of theunit electrode portion 191 and formed to face the oblique side Eb, asecond vertex formed on a horizontal side of the unit electrode portion191, and a third vertex formed on a vertical side of the unit electrodeportion 191. The oblique side Eb extends toward a direction crossing anextending direction of the branches 197 of each of the subregions A1,A2, A3, and A4. More specifically, a direction in which the oblique sideEb extends may be mostly perpendicular to the extending direction of thebranches 197. The planar portion 198 may form an outer circumference ofthe unit electrode portion 191 and may include two sides connected tothe oblique side Eb.

Among the vertices of the planar portion 198, the vertex formed on thehorizontal side or the vertical side of the unit electrode portion 191is formed on the end portion of the oblique side Eb, and may be disposedbetween the vertex of the unit electrode portion 191 and an end portionof the vertical stem of the cross-shaped stem 195. Accordingly, an areaoccupied by the planar portion 198 in the subregions A1, A2, A3, and A4may be equal to or less than about 50%. In this case, a distance betweenthe oblique side Eb of the planar portion 198 and a vertex formed toface the oblique side Eb may be equal to or less than about 50% of adiagonal length of each of the subregions A1, A2, A3, and A4.

An angle between the oblique side Eb of the planar portion 198 and anextending direction of the horizontal stem of the cross-shaped stem 195,i.e. the first direction D1, may be in a range of about 40° to about50°. Particularly, the oblique side Eb of the planar portion 198 may besubstantially parallel to the oblique side Ea of the corner portion 261c of the protrusion 261. The oblique side Ea of the corner portion 261 cof the protrusion 261 is overlapped with an interior region of theplanar portion 198.

As such, in the case in which the unit electrode portion 191 includesthe planar portion 198, liquid crystal alignment controllability may beimproved by the action of a fringe field generated by the oblique sideEb of the planar portion 198, thereby further improving thetransmittance of the display device.

Referring to FIG. 6 described above, the liquid crystal molecules 31around edges of the branches 197 have a tendency of being aligned in adirection that faces the inside of the branches 197 instead of beingaligned in the extending direction of the branches 197. Accordingly, thetransmittance may be partially deteriorated around the edge of thebranches 197, so a space therearound may be seen as a dark space.

However, in the case in which the unit electrode portion 191 includesthe planar portion 198 as in the present exemplary embodiment of thepresent disclosure, the dark space around the branches 197 may bereduced, so overall transmittance of the unit region SP may be improved.

Since slits or branches 197 are not formed on the planar portion 198,the controllability may not be sufficient when the liquid crystalmolecules 31 are realigned. However, the planar portion 198 is disposedin a position adjacent to the corner portion 261 c of the protrusion261, and the corner portion 261 c enhances the controllability of theliquid crystal molecules 31 so the alignment direction of the liquidcrystal molecules 31 corresponding to the planar portion 198 may becontrolled effectively. Accordingly, sufficient transmittance may beachieved.

The planar portion 198 is physically and electrically connected to thecross-shaped stem 195 with a separate connector (not illustrated).Referring to FIG. 9, the planar portion 198 may be spaced apart from theend portions of the branches 197 with a predetermined distancetherebetween, but the present exemplary is not limited thereto. Forexample, the planar portion 198 may be connected thereto.

Next, referring to FIG. 10, a display device according to the presentexemplary embodiment is the same as most of the aforementioned exemplaryembodiment illustrated in FIG. 9, while sides of end portions of thebranches 197 of the unit electrode portion 191 and an outer side of theplanar portion 198 may not be overlapped with the protrusion 261. Adistance between the sides of the end portions of the branches 197 andthe outer side of the planar portion 198, and an inner edge of theprotrusion 261, may be greater than or equal to 0 μm. According to thepresent exemplary embodiment, the display device may have improved sidevisibility.

Next, referring to FIG. 11, a display device according to the presentexemplary embodiment is the same as most of the aforementioned exemplaryembodiment illustrated in FIG. 9, while at least one planar portion 198of the unit region SP may be connected to end portions of the branches197 adjacent thereto.

Next, referring to FIG. 12, a display device according to the presentexemplary embodiment is the same as most of the aforementioned exemplaryembodiment illustrated in FIG. 9, while at least one corner portion 261c of the protrusion 261 disposed in the unit region SP may be omitted.According to the present exemplary embodiment, a slit is not formed inthe planar portion 198, so the above-described dark space may be reducedto improve overall transmittance.

Hereinafter, a detailed structure of the unit region SP of a displaydevice according to an exemplary embodiment of the present disclosure isdescribed with reference to FIG. 13 to FIG. 15 along with theabove-described drawings. The same constituent elements as in theabove-described exemplary embodiments are designated by the samereference numerals. Thus, descriptions thereof are omitted, and detaileddescriptions focusing on different elements are provided.

Referring to FIG. 13 and FIG. 14, a display device according to thepresent exemplary embodiment is the same as most of the aforementionedexemplary embodiment illustrated in FIG. 6, while the protrusion 261 mayhave a partially different structure. The protrusion 261 according tothe present exemplary embodiment may include a sloped corner portion 261d instead of the above-described corner portion 261 c.

Referring to FIG. 13, when viewed from a planar structure, theprotrusion 261 includes a pair of horizontal portions 261 a configuredto face each other with respect to the center C of the unit region SPand each including a side parallel to the first direction D1, a pair ofvertical portions 261 b configured to face each other with respect tothe center C of the unit region SP and each including a side parallel tothe second direction D2, and the sloped corner portion 261 d includingan oblique side Ec parallel to a direction that is oblique to the firstand second directions D1 and D2. Except for the sloped corner portion261 d, characteristics of the protrusion 261 including the horizontalportion 261 a, the vertical portion 261 b, and the like are the same asin the aforementioned description, so herein, detailed descriptions willbe omitted.

The sloped corner portion 261 d is disposed in at least one corner ofthe unit region SP, and is interposed between the horizontal portion 261a and the vertical portion 261 b adjacent to each other. The slopedcorner portion 261 d may be in a shape of substantially a triangleincluding the oblique side Ec. Two sides of the sloped corner portion261 d except the oblique side Ec may be substantially parallel to thefirst and second directions D1 and D2, respectively. The oblique side Ecof the sloped corner portion 261 d, as illustrated in FIG. 13, may beconnected to adjacent sides of the horizontal portion 261 a and thevertical portion 261 b, or spaced apart therefrom with a predetermineddistance therebetween.

The pair of horizontal portions 261 a, the pair of vertical portions 261b, and four sloped corner portions 261 d may be connected to each other,and substantially constitute a closed curve. In this case, an outercircumference of the protrusion 261 may be substantially in a shape of aquadrangle.

The oblique side Ec of the sloped corner portion 261 d may form an angleAng2 with respect to the first direction D1 to be equal to or greaterthan about 40° and less than about 90°. Herein, the angle Ang2 is anacute angle. An extending direction of the oblique side Ec may cross thetilting directions a1, a2, a3, and a4 of the liquid crystal molecules 31in subregions A1, A2, A3, and A4, respectively, and more specifically,an angle of the crossing may be substantially vertical.

Referring to FIG. 13 and FIG. 14, a distance d2 between the oblique sideEc of the sloped corner portion 261 d and a vertex formed to face theoblique side Ec may be equal to or less than about 50% of a diagonallength of each of the subregions A1, A2, A3, and A4.

The horizontal portion 261 a and the vertical portion 261 b of theprotrusion 261 may be formed around at least a part of a lighttransmitting region of the unit region SP. FIG. 13 illustrates anexample in which the horizontal portion 261 a and the vertical portion261 b of the protrusion 261 form a closed curve surrounding all ofsubregions A1, A2, A3, and A4 included in the unit region SP. Thehorizontal portion 261 a and the vertical portion 261 b of theprotrusion 261 may correspond to a light blocking region surrounding alight transmitting region, and most of the sloped corner portion 261 dmay correspond to a light transmitting region. That is, a region atwhich the sloped corner portion 261 d is positioned may transmit lightto display an image.

Referring to FIG. 13 and FIG. 14, when viewed from a cross-sectionalstructure as in the above-described exemplary embodiment, the horizontalportion 261 a and the vertical portion 261 b of the protrusion 261includes a lateral surface Sa that is a slope obliquely tilted withrespect to a bottom surface of the protrusion 261, and the sloped cornerportion 261 d of the protrusion 261 includes a lateral surface Sb thatis a slope obliquely tilted with respect to a bottom surface of theprotrusion 261. Inclinations of the lateral surfaces Sa and Sb withrespect to the bottom surface of the protrusion 261 may be differentfrom each other, while an inclination of the lateral surface Sb withrespect to the bottom surface of the protrusion 261 is more gentle thanthat of the lateral surface Sa.

A cross-sectional angle Ang3 between the lateral surface Sb of thesloped corner portion 261 d and a bottom surface of the protrusion 261may be in a range of about 1° to about 2°, but is not limited thereto,and may vary depending on a material characteristic or a manufacturingprocess of the protrusion 261.

A maximum height H2 of the sloped corner portion 261 d from a bottomsurface thereof, i.e., a maximum thickness, may be equal to or less than0.5 μm, but is not limited thereto, and may vary depending on a designcondition. Particularly, the sloped corner portion 261 d corresponds toa light transmitting region of each of subregions A1, A2, A3, and A4 ofthe unit region SP, so a thickness of the sloped corner portion 261 dmay be reduced to achieve a predetermined transmittance.

An outer circumference of the sloped corner portion 261 d is connectedto the horizontal portion 261 a or the vertical portion 261 b of theprotrusion 261. A maximum thickness of the sloped corner portion 261 maybe less than a maximum thickness of the horizontal portion 261 a or thevertical portion 261 b of the protrusion 261.

The oblique side Ec of the sloped corner portion 261 d of the protrusion261 is a bottom side of the lateral surface Sb of the sloped cornerportion 261 d.

When the alignment of the liquid crystal molecules 31 substantiallyperpendicular to a plane of the display panel 300 is determined as areference alignment, the sloped corner portion 261 d controls the liquidcrystal molecules 31 adjacent to the lateral surface Sb to have apretilt toward each interior portion of the subregions A1, A2, A3, andA4 even when an electric field is not generated in the liquid crystallayer. A pretilt direction of the liquid crystal molecules 31 is adirection forming an acute angle with respect to a reference alignmentdirection DR substantially perpendicular to the plane of the displaypanel 300, and such an acute pretilt angle Ap therebetween may be, forexample, in a range of about 1° to about 2°.

The pretilt of the liquid crystal molecules 31 by the protrusion 261 mayprovide faster alignment of the liquid crystal molecules 31 disposed ineach of the subregions A1, A2, A3, and A4 in the respective tiltingdirections a1, a2, a3, and a4 when an electric field is generated in theliquid crystal layer.

Particularly, since the direction perpendicular to the oblique side Ecof the sloped corner portion 261 d substantially faces the center C ofthe unit region SP, the liquid crystal molecules 31 positioned aroundthe sloped corner portion 261 d already have a pretilt in the tiltingdirections a1, a2, a3, and a4 in which the liquid crystal molecules 31are tilted when an electric field is generated in the liquid crystallayer. Accordingly, the liquid crystal molecules 31 may have a fasterrealignment speed, so response speed and transmittance thereof may beimproved.

In the case in which the angle Ang2 formed between the oblique side Ecof the sloped corner portion 261 d and the first direction D1 is about45°, the sloped corner portion 261 d may control the liquid crystalmolecules 31 disposed in the subregions A1, A2, A3, and A4 to be alignedfaster in a direction toward the center C thereof. In the case in whichthe angle Ang2 is greater than about 45°, the sloped corner portion 261d may control the liquid crystal molecules 31 to have an angle less thanabout 45° between the tilting directions a1, a2, a3, and a4 thereof andthe first direction D1. In this case, since the liquid crystal molecules31 may be tilted in a direction closer to the first direction D1 thanthe second direction D2 when an electric field is generated in theliquid crystal layer, side visibility may be improved.

If the liquid crystal layer of the display panel 300 is pressed by anexternal pressure, and thus alignment of the liquid crystal molecules 31is disordered, even when the external pressure is removed, the alignmentof the liquid crystal molecules 31 may not be recovered, thereby beingseen as spots. However, according to the exemplary embodiment of thepresent disclosure, the protrusion 261 may control the alignment of theadjacent liquid crystal molecules 31 that are adjacent thereto in apredetermined direction. This facilitates the recovery of the liquidcrystal molecules 31 in each of the subregions A1, A2, A3, and A4 to theoriginal alignment direction. That is, after an external pressure isremoved, the recovery speed at which the alignment of the liquid crystalmolecules 31 returns from disorder is improved. Particularly, the slopedcorner portion 261 d of the protrusion 261 may support faster recoveryto the tilting directions at, a2, a3, and a4.

As such, according to the exemplary embodiment of the presentdisclosure, when an image is displayed by generating an electric fieldin the liquid crystal layer, the liquid crystal molecules 31 may berealigned faster in a target realignment direction by the action of bythe protrusion 261, so the transmittance may be further improved, and animage closer to a target luminance may be displayed, thereby improvingthe display quality. Further, sufficient controllability of the liquidcrystal molecules 31 may be secured without including an alignment aidto an alignment layer or a liquid crystal layer, unlike a conventionalart, so a display device having improvements in liquid crystal alignmentcontrollability and transmittance may be provided without adding acomplex manufacturing process.

Next, referring to FIG. 15, a display device according to the presentexemplary embodiment is the same as most of the aforementioned exemplaryembodiment illustrated in FIG. 13 and FIG. 14, while a structure of theunit electrode portion 191 may be different.

The unit electrode portion 191 is the same as most of the aforementionedexemplary embodiment, while the unit electrode portion 191 may includeat least one planar portion 198, disposed in at least one of fourcorners thereof as in the exemplary embodiment illustrated in FIG. 9. Inthe case in which the unit electrode portion 191 is of substantially aquadrangle, the planar portion 198 is disposed in at least one corner ofa quadrangle. FIG. 15 illustrates an example in which each planarportion 198 is disposed on all of the four corners of the unit electrodeportion 191.

A characteristic of the planar portion 198 is the same as that of theabove-described exemplary embodiment illustrated in FIG. 9, so herein,detailed descriptions are omitted.

A distance d2 between the oblique side Ec of the sloped corner portion261 d and a vertex formed to face the oblique side Ec may be less than adistance between the oblique side Eb of the planar portion 198 and avertex formed to face the oblique side Eb. That is, the oblique side Ecof the sloped corner portion 261 d may be overlapped with an interiorportion of the planar portion 198.

The oblique side Ec of the sloped corner portion 261 d may besubstantially parallel to the oblique side Eb of the planar portion 198.

In the case in which the unit electrode portion 191 includes the planarportion 198, liquid crystal alignment controllability may be improved bythe action of a fringe field by the oblique side Eb of the planarportion 198, so transmittance of the display device may be furtherimproved. Further, since the planar portion 198 may be formed in a shapeof a unitary plate without an opening or the branches 197, theaforementioned dark space does not exist around the branches 197, sooverall transmittance of the unit region SP may be improved.

Since a slit or the branches 197 is not formed on the planar portion198, the controllability may not be sufficient when the liquid crystalmolecules 31 are realigned. However, because at least a part of theplanar portion 198 overlaps the sloped corner portion 261 d, liquidcrystal alignment controllability in the case of realigning the liquidcrystal molecules 31 may be improved by a pretilt of the liquid crystalmolecules 31 by the action of the sloped corner portion 261 d.Accordingly, an alignment direction of the liquid crystal molecules 31positioned to correspond to the planar portion 198 may be controlledeffectively, so sufficient transmittance may be achieved.

In a manufacturing process of the display device according to anexemplary embodiment of the present disclosure, the protrusion 261 maybe formed by coating an organic material and then by using aphotolithographic process with exposure using a photomask anddevelopment. In this case, light transmittances of photomaskscorresponding to the horizontal portion 261 a and the vertical portion261 b of the protrusion 261 may be constant, and light transmittance ofthe photomask corresponding to the sloped corner portion 261 d may bedifferent from those of photomasks corresponding to the horizontalportion 261 a and the vertical portion 261 b. In the case in which theorganic material has negative photosensitivity, such that a portion ofthe organic material to which light is irradiated remains, lighttransmittance of a photomask corresponding to the sloped corner portion261 d may be lower than light transmittances of photomasks correspondingto the horizontal portion 261 a and vertical portion 261 b, so lesslight may be irradiated to an organic material during an exposureprocess.

To make the lateral surface Sb of the sloped corner portion 261 dgentle, a region of a photomask corresponding to the sloped cornerportion 261 d may have variable light transmittance according to aposition therein. For example, in the case of a material having thenegative photosensitivity, such that a portion to which light isirradiated remains, light transmittance of a photomask corresponding tothe sloped corner portion 261 d may decrease from a vertex configuredtoward the oblique side Ec of the sloped corner portion 261 d toward theoblique side Ec. Light transmittance of a photomask corresponding to thesloped corner portion 261 d may vary in a stepwise way or in a gradualway.

Besides such photolithography process, various methods for forming theprotrusion 261 having different thicknesses according to a positiontherein may be employed.

Next, a structure of one pixel of a display device according to anexemplary embodiment of the present disclosure is described withreference to FIG. 16 to FIG. 20 along with the above-described drawings.

First, referring to FIG. 16 to FIG. 18, the display device according tothe exemplary embodiment of the present disclosure is a liquid crystaldisplay including the display panel 300. The display panel 300 mayinclude a lower display panel 100 and an upper display panel 200configured to face each other when viewed from a cross-sectionalstructure, and a liquid crystal layer 3 interposed therebetween.

The lower display panel 100 includes a substrate 110, and a plurality ofgate lines 121 and a gate conductor including a reference voltage line131 disposed on an inner plane of the substrate 110. Herein, an innerplane of the substrate 110 designates a plane configured to face theliquid crystal layer 3, and it designates the same hereinafter.

The gate line 121 mainly extends in the first direction D1, which is ahorizontal direction, and includes a first gate electrode 124 a, asecond gate electrode 124 b, and a third gate electrode 124 c.

The reference voltage line 131 may be spaced apart from the gate lines121, and may mainly extend in a direction parallel to the firstdirection D1. The reference voltage line 131 may transfer a referencevoltage that may be an AC voltage or a constant DC voltage such as acommon voltage V_(com) or the like.

The reference voltage line 131 may include an extension portion 131 amainly extending in a horizontal direction, a vertical portion 131 bprotruding upward or downward from the extension portion 131 a andmainly extending in a direction parallel to the second direction D2, anda horizontal portion 131 c connected to the vertical portion 131 b andmainly extending in the first direction D1.

A gate insulating layer 140 is disposed on the gate conductor, and asemiconductor layer including a first semiconductor 154 a, a secondsemiconductor 154 b, and a third semiconductor 154 c is disposedthereon. The first semiconductor 154 a and the second semiconductor 154b may be connected to each other. The first semiconductor 154 a mayoverlap the first gate electrode 124 a, the second semiconductor 154 bmay overlap the second gate electrode 124 b, and the third semiconductor154 c may overlap the third gate electrode 124 c.

The semiconductor layer may include amorphous silicon, polycrystallinesilicon, an oxide semiconductor, or the like.

A plurality of ohmic contact elements 163 a and 165 a may be disposed onthe semiconductor layer. The ohmic contact elements 163 a and 165 a maybe formed of a silicide or a material such as n+ hydrogenated amorphoussilicon doped with high density n-type impurities. The ohmic contactelements 163 a and 165 a may be omitted. A plurality of data lines 171including a first source electrode 173 a and a second source electrode173 b, and a data conductor including a first drain electrode 175 a, asecond drain electrode 175 b, a third source electrode 173 c, and athird drain electrode 175 c are disposed on the ohmic contact elements163 a and 165 a and the gate insulating layer 140.

The data lines 171 may transfer a data signal and may mainly extend inthe second direction D2, which is a vertical direction, and may crossthe gate lines 121 and the reference voltage line 131.

The first source electrode 173 a protrudes from the data lines 171toward the first gate electrode 124 a and is configured to face thefirst drain electrode 175 a, and the second source electrode 173 bprotrudes from the data lines 171 toward the second gate electrode 124 band is configured to face the second drain electrode 175 b.

The first source electrode 173 a and the second source electrode 173 bare connected to each other, and the second drain electrode 175 b andthe third source electrode 173 c are connected to each other. The thirdsource electrode 173 c and the third drain electrode 175 c areconfigured to face each other.

Among end portions of the third drain electrode 175 c, an end portionthat is not formed to face the third source electrode 173 c may beadjacent to or may be overlapped with the reference voltage line 131.

The first gate electrode 124 a, the first source electrode 173 a, andthe first drain electrode 175 a constitute a first thin film transistorQa as a first switching element along with the first semiconductor 154a. The second gate electrode 124 b, the second source electrode 173 b,and the second drain electrode 175 b constitute a second thin filmtransistor Qb as a second switching element along with the secondsemiconductor 154 b. The third gate electrode 124 c, the third sourceelectrode 173 c, and the third drain electrode 175 c constitute a thirdthin film transistor Qc as a voltage-dividing switching element alongwith the third semiconductor 154 c.

Channels of the first thin film transistor Qa, the second thin filmtransistor Qb, and the third thin film transistor Qc are respectivelyformed in first, second, and third semiconductors 154 a, 154 b, and 154c that are interposed between first, second, and third source electrodes173 a, 173 b, and 173 c, and first, second, and third drain electrodes175 a, 175 b, and 175 c.

The gate lines 121, the reference voltage line 131, and the first tothird thin film transistors Qa, Qb, and Qc may be disposed in theabove-described thin film transistor region TRA.

A first insulating layer 180 a is disposed on the data conductor andexposed parts of semiconductors 154 a, 154 b, and 154 c. The firstinsulating layer 180 a may be formed of an organic insulating materialor an inorganic insulating material, and may include a single layer or amulti-layer.

An organic layer may be disposed on the first insulating layer 180 a.For example, the organic layer may include a color filter 230. Lightpassing through the color filter 230 may display one color of primarycolors, such as three primary colors, red, green, and blue, four primarycolors, or the like. The colors displayed by the color filter 230 arenot limited to the three primary colors including red, green, and blue,and may include one of primary color including cyan, magenta, yellow, orwhite series.

The color filter 230 may extend along each pixel array. The color filter230 may include an opening (not illustrated) disposed on portions of thedrain electrodes 175 a, 175 b, and 175 c.

A second insulating layer 180 b may be disposed on the color filter 230.The second insulating layer 180 b may include an inorganic insulatingmaterial or an organic insulating material. The second insulating layer180 b serves as an overcoat for the color filter 230 and may prevent thecolor filter 230 from being exposed, so an impurity, such as a pigmentof the color filter 230, may be prevented from flowing into the liquidcrystal layer 3. The second insulating layer 180 b may be omitted.

The first insulating layer 180 a and the second insulating layer 180 binclude a first contact hole 185 a exposing a part of the first drainelectrode 175 a and a second contact hole 185 b exposing a part of thesecond drain electrode 175 b. The first and second contact holes 185 aand 185 b may be respectively disposed in an opening of the color filter230.

The gate insulating layer 140 and the first and second insulating layers180 a and 180 b may further include a third contact hole 185 csimultaneously exposing parts of the third drain electrode 175 c and thereference voltage line 131.

A pixel electrode layer including a plurality of pixel electrodes andconnecting electrodes 192 and 193 is disposed on the second insulatinglayer 180 b.

A pixel electrode disposed in one pixel PX may be formed as onecontinuous electrode including all parts that are connected to eachother, or may be formed to include a plurality of subpixel electrodes.In the present exemplary embodiment, descriptions are focused on anexample in which a pixel electrode includes a first subpixel electrode191 a and a second subpixel electrode 191 b.

One pixel PX, as described above, includes a plurality of unit regionsSP. Accordingly, one pixel electrode may include a plurality of unitelectrode portions 191 as in the above-described exemplary embodiments.Further, in the case in which one pixel electrode includes separatedfirst and second subpixel electrodes 191 a and 191 b, each of thesubpixel electrodes 191 a and 191 b may include a plurality of unitelectrode portions 191 as in the above-described exemplary embodimentsto secure sufficient liquid crystal alignment controllability. FIG. 16and FIG. 17 illustrate an example in which the first subpixel electrode191 a includes four unit electrode portions 191 connected to each otherand the second subpixel electrode 191 b includes six unit electrodeportions 191 connected to each other.

A number of unit electrode portions 191 included in one pixel PX may bevariously determined according to an area of one pixel PX inconsideration of liquid crystal alignment controllability.

The unit electrode portions 191 may be arranged substantially in amatrix form, and the unit electrode portions 191 that are adjacentlydisposed may be connected to each other by a connector (notillustrated). The connector may be disposed on an extending line of thecross-shaped stems 195 of the unit electrode portions 191.

A structure of the unit electrode portions 191 is the same as that ofabove-described exemplary embodiments, so herein, detailed descriptionsare omitted.

Referring to FIG. 16, the cross-shaped stems 195 included in the unitelectrode portions 191 may not have a constant width, but may have awidth that is increased toward a center thereof, but are not limitedthereto.

The first subpixel electrode 191 a and the second subpixel electrode 191b may be configure to face each other with the gate line 121, thereference voltage line 131, and the first to third thin film transistorsQa, Qb, and Qc interposed therebetween, but a configuration thereof isnot limited to the illustrated exemplary embodiments and may be modifiedin various ways.

The first and second subpixel electrodes 191 a and 191 b are physicallyand electrically connected to the first and second drain electrodes 175a and 175 b through contact holes 185 a and 185 b, respectively. Thefirst subpixel electrode 191 a may receive a data voltage from the firstdrain electrode 175 a, and the second subpixel electrode 191 b mayreceive a voltage divided between a data voltage transferred through thesecond drain electrode 175 b and a reference voltage transferred throughthe reference voltage line 131.

The third drain electrode 175 c and the reference voltage line 131 maybe electrically connected to each other in the third contact hole 185 cthrough the connecting electrode 192.

The connecting electrode 192 may include a contact portion 192 ccontacting the third drain electrode 175 c and a part of the referencevoltage line 131, a vertical portion 192 a extending upward from thecontact portion 192 c, and a vertical portion 192 b extending downwardfrom the contact portion 192 c. The vertical portions 192 a and 192 bare spaced apart from the first and second subpixel electrodes 191 a and191 b, and may extend in a direction substantially parallel to thesecond direction D2. The vertical portions 192 a and 192 b may beoverlapped with the data lines 171. The vertical portions 192 a and 192b electrically connect a plurality of reference voltage lines 131, so avariation of the reference voltage transferred by the reference voltageline 131 may be prevented. Further, the vertical portions 192 a and 192b block an electric field generated by a data voltage of the data line171 and prevent a voltage of an adjacent pixel electrode from beingfluctuated by the variation of the data voltage.

The connecting electrode 193 may be disposed alternately with theconnecting electrode 192 toward the first direction D1, and may beconfigured to face each other with a pixel electrode interposedtherebetween. A structure and a function of the connecting electrode 193may be substantially the same as those of the connecting electrode 192.

The pixel electrode layer may include a transparent conductive materialsuch as indium tin oxide (ITO), indium zinc oxide (IZO), a metal thinfilm, or the like.

The structure of the pixel PX described above in the present exemplaryembodiment is merely one example, and numerous variations are possible.

A light blocking member 221 is disposed on the pixel electrode layer.The light blocking member 221, which is also referred to as a blackmatrix, may block light transmission. Accordingly, a region at which thelight blocking member 221 is formed is included in a light blockingregion.

According to the present exemplary embodiment, the light blocking member221 may include a main light blocker 221 a, a spacer 221 b, and theprotrusion 261 as in the above-described exemplary embodiments.

The main light blocker 221 a may include a part located in a lightblocking region including regions at which the first to third thin filmtransistors Qa, Qb, and Qc are disposed, and may have a substantiallyflat upper surface. The main light blocker 221 a may block light leakagebetween light transmitting regions at which the first and secondsubpixel electrodes 191 a and 191 b are respectively disposed, andbetween light transmitting regions of pixels PX adjacent to each other.

The main light blocker 221 a may include a part covering the contactholes 185 a, 185 b, and 185 c. The part may smoothen step portionsbetween upper portions of the contact holes 185 a, 185 b, and 185 c byfilling the contact holes 185 a, 185 b, and 185 c, to block lightleakage therearound.

The spacer 221 b may be connected to the main light blocker 221 a, butthe present exemplary embodiment is not limited thereto.

The spacer 221 b is disposed in the light blocking region, andparticularly, may be disposed on the upper portions of the first tothird thin film transistors Qa, Qb, and Qc, and/or on the signal linessuch as the gate line 121, the reference voltage line 131, and the dataline 171.

The spacer 221 b in a general state may serve as a main spacermaintaining and supporting a cell gap between the upper display panel200 and the lower display panel 100, and may be a sub-spacer maintainingand supporting a cell gap between the upper display panel 200 and thelower display panel 100 in the case in which a distance between theupper display panel 200 and the lower display panel 100 becomes narrowerwhen external pressure is applied to the display device. In the case inwhich the spacer 221 b serves as the sub-spacer, an upper portion of thespacer 221 b may not be in a contact with an internal surface of theupper display panel 200 when no pressure is applied.

The protrusion 261 is simply illustrated in FIG. 17 omitting detailsthereof, but may have structures according to those of above-describedvarious exemplary embodiments. The liquid crystal molecules 31 adjacentto the lateral surface Sa of the protrusion 261 may have an initialalignment in a direction substantially perpendicular to the lateralsurface Sa, and may mainly maintain the alignment state even when anelectric field is not generated in the liquid crystal layer 3. Othercharacteristics and effects of the protrusion 261 are the same as thoseof the above descriptions, so herein, detailed descriptions are omitted.

The protrusion 261 is disposed in the same layer as the main lightblocker 221 a or the spacer 221 b of the light blocking member 221, andmay include the same material as the main light blocker 221 a or thespacer 221 b of the light blocking member 221. A maximum thickness ofthe protrusion 261 may be thicker than, similar to, or thinner than anaverage thickness of the main light blocker 221 a. FIG. 18 illustratesan example in which a maximum thickness of the protrusion 261 is thickerthan the main light blocker 221 a therearound, but the present exemplaryembodiment is not limited thereto.

The light blocking member 221 may be formed by using one photomask.

Since the light blocking member 221 has various thicknesses as in themain light blocker 221 a, the spacer 221 b, and the protrusion 261, thephotomask may have light transmittances that are differently adjustedaccording to a corresponding position. Specifically, in the case inwhich a material of the light blocking member 221 has negativephotosensitivity, a region of a photomask corresponding to the spacer221 b having a maximum thickness may have highest light transmittance,and regions corresponding to the main light blocker 221 a and theprotrusion 261 may have lower light transmittance. In this case, theregions of the photomask corresponding to the main light blocker 221 aand the protrusion 261 may have a halftone or a plurality of slits tocontrol light transmittance. In the case in which thicknesses of themain light blocker 221 a and the protrusion 261 are different from eachother, a region of the photomask corresponding to a thicker one may havehigher light transmittance than light transmittance of a region of thephotomask corresponding to a thinner one.

Particularly, in the case in which the above-described protrusion 261includes the sloped corner portion 261 d, a photomask corresponding tothe sloped corner portion 261 d may have lower light transmittance thana photomask corresponding to other portions of the protrusion 261, forexample, the horizontal portion 261 a or the vertical portion 261 b. Asdescribed above, a light transmittance of the photomask decreases towarda direction of decreasing thickness of the sloped corner portion 261 d,so the sloped corner portion 261 d may form a gentle inclination. Assuch, the region of the photomask having light transmittance that isgradually changed may be formed by gradually controlling a number ofslits or a tonal strength of the halftone.

The light blocking member 221 may include a pigment, such as carbonblack, and a photosensitive organic material.

In the case in which the color filter 230 and/or the light blockingmember 221 along with first to third thin film transistors Qa, Qb, andQc are disposed in the lower display panel 100 as in an exemplaryembodiment of the present disclosure, alignments between the lightblocking member 221 and the color filter 230, and between the pixelelectrode and thin film transistors Qa, Qb, and Qc, may be facilitated,thereby reducing an alignment error.

An alignment layer 11 is disposed on the light blocking member 221, andthe alignment layer 11 may be a vertical alignment layer.

The upper display panel 200 includes a substrate 210, and an opposedelectrode 270 may be disposed on an inner surface of the substrate 210.The opposed electrode 270 may be formed in a shape of a planar unitaryplate on an entire surface of the substrate 210. The opposed electrode270 may transfer a common voltage V_(com) having a constant voltage. Theopposed electrode 270 may include a transparent conductive material,such as ITO and IZO, a metal thin film, or the like.

An alignment layer 21 is disposed on the opposed electrode 270, and thealignment layer 21 may be a vertical alignment layer.

The liquid crystal layer 3 includes a plurality of liquid crystalmolecules 31. The liquid crystal molecules 31 may have negativedielectric anisotropy, and may be initially aligned in a direction thatis substantially perpendicular to a plane of the substrates 110 and 210when an electric field is not generated in the liquid crystal layer 3.The liquid crystal molecules 31, particularly the liquid crystalmolecules 31 positioned around the protrusion 261, have a pretilt in adirection substantially perpendicular to a surface of the protrusion261.

The pixel electrode and the opposed electrode 270 may control analignment direction of the liquid crystal molecules 31 by generating anelectric field in the liquid crystal layer 3 with an applied voltage tothereby display an image.

FIG. 19 illustrates a cross-sectional structure of a display deviceaccording to an exemplary embodiment that is different from theexemplary embodiment illustrated in FIG. 16 and FIG. 17. Referring toFIG. 19 along with FIG. 16 and FIG. 17, the present exemplary embodimentis the same as most of the aforementioned exemplary embodimentillustrated in FIG. 18, while the color filter 230 may be disposed inthe upper display panel 200.

The lower display panel 100 may include a third insulating layer 180 cinterposed between the first insulating layer 180 a and the secondinsulating layer 180 b. The third insulating layer 180 c may include anorganic material and may provide a flat upper surface.

FIG. 20 illustrates a cross-sectional structure of a display deviceaccording to an exemplary embodiment that is different from exemplaryembodiment illustrated in FIG. 16 and FIG. 17. Referring to FIG. 20along with FIG. 16 and FIG. 17, the present exemplary embodiment is thesame as most of the aforementioned exemplary embodiment illustrated inFIG. 19, while a light blocking member 220 may be disposed in the upperdisplay panel 200. The light blocking member 220 may be interposedbetween the substrate 210, and the color filter 230 and may be disposedon the color filter 230. An overcoat 250 may be disposed on the lightblocking member 220 and the color filters 230, and the opposed electrode270 may be disposed on the overcoat 250. The light blocking member 220may have a structure and a function that are similar to those of theabove-described main light blocker 221 a.

The lower display panel 100 is mostly the same as that of the abovedescriptions, while a spacer 222 and the protrusion 261 may be disposedon the pixel electrode layer.

The spacer 222 may have an island shape. The spacer 222 may be disposedin a light blocking region of the pixel PX, and particularly, may bedisposed on upper portions of the first to third thin film transistorsQa, Qb, and Qc, and/or signal lines such as the gate line 121, thereference voltage line 131, and the data line 171. In addition, thespacer 222 may have a structure and a function that are similar to thoseof the above-described spacer 221 b.

The protrusion 261 may have a structure and a function according to thevarious exemplary embodiments described above. The protrusion 261 isdisposed in the same layer as the spacer 222, and may include the samematerial as the spacer 222. A maximum thickness of the protrusion 261 isless than a thickness of the spacer 222.

The protrusion 261 and the spacer 222 may be formed by using onephotomask. For example, in the case in which a material forming theprotrusion 261 and the spacer 222 has negative photosensitivity, aregion of the photomask corresponding to the spacer 221 b having amaximum thickness may have highest light transmittance, and a region ofthe photomask corresponding to the protrusion 261 may have lower lighttransmittance. In this case, the region of the photomask correspondingto the protrusion 261 may have a halftone or a plurality of slits tocontrol light transmittance.

Particularly, in the case in which the above-described protrusion 261includes the sloped corner portion 261 d, a photomask corresponding tothe sloped corner portion 261 d may have lower light transmittance thana photomask corresponding to other portions of the protrusion 261, forexample, the horizontal portion 261 a or the vertical portion 261 b.Further, as described above, light transmittance of the photomaskdecreases toward a direction of decreasing thickness of the slopedcorner portion 261 d, so the sloped corner portion 261 d may form agentle inclination. As such, the region of the photomask having lighttransmittance that is gradually changed may be formed by graduallycontrolling a number of slits or a tonal strength of the halftone.

A material included in the spacer 222 and the protrusion 261 may betransparent or may include a light blocking material. Even in the casein which the protrusion 261 includes a transparent material, a region atwhich the protrusion 261 is formed may not transmit most of the light,so may be mostly included in the light blocking region.

According to the exemplary embodiment of the present disclosure, theprotrusion 261 may be interposed between the pixel electrode includingthe unit electrode portion 191 and the liquid crystal layer 3. However,in some cases, it may be disposed in a layer interposed between thesubstrate 110 and the pixel electrode. In the case in which theprotrusion 261 is interposed between the substrate 110 and the pixelelectrode, a step portion of the protrusion 261 is transferred to anupper layer of the protrusion 261, and thus an uppermost layer adjacentto the liquid crystal layer 3 protrudes to the liquid crystal layer 3,so liquid crystal molecules 31 may have a pretilt.

While the present system and method have been described in connectionwith exemplary embodiments, the present system and method are notlimited to the disclosed embodiments but, on the contrary, cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

DESCRIPTION OF SYMBOLS

-   -   100, 200, 300: display panel    -   191: unit electrode portion    -   220, 221: light blocking member    -   222: spacer    -   230: color filter    -   261: protrusion    -   270: opposed electrode

What is claimed is:
 1. A display device comprising: a first substrateincluding a plurality of unit regions; a unit electrode portion disposedon the first substrate and disposed in one unit region of the pluralityof unit regions, the unit electrode having a substantially rectangularshape having four corners; an opposed electrode facing the unitelectrode portion; and a liquid crystal layer including a plurality ofliquid crystal molecules interposed between the unit electrode portionand the opposed electrode, wherein the unit region comprises a pluralityof subregions at which the liquid crystal molecules are tilted indifferent directions from each other when an electric field is generatedin the liquid crystal layer, the unit electrode portion includes a stemdisposed between adjacent subregions of the unit region and continuouslycrossing through a center of the unit region, a plurality of branchesextending from the stem, and at least one planar portion disposed in atleast one corner of the unit electrode portion, and the planar portionincludes an oblique side extending in a direction perpendicular to anextending direction of the branches.
 2. The display device of claim 1,wherein the oblique side extends toward an oblique direction withrespect to an extending direction of the stem, and the oblique side isdisposed internally in the subregions.
 3. The display device of claim 2,wherein the oblique side is spaced apart from the branches facing theoblique side.
 4. The display device of claim 1, wherein a ratio of anoccupied are of the planar portion in a corresponding subregion is equalto or less than about 50%.
 5. The display device of claim 1, wherein theplanar portion has a substantially triangular shape.